11 %

I believe it will be 11% with one less tooth on the front sprocket. If not 11%, then very close to that.

 

I don't think that much. Here's a little spreadsheet I put together to calculate this sort of thing. I set it up for a one tooth drop in the front.

 

I believe the speedo is off by about 10% from the factory... reason, top speed on the bike is tested at 167mph but he speedo reads 180. i dont think when it says 180 it is accurate, more like 165-167..
my question is why do bikes speedos run optimistic in the first place? safety mechanism? I could be wrong, anyone test the accuracy of the speedo?

 

So....if the speedo is off quite a bit from the factory....usually shows an indicated speed faster than you are really going......will dropping a tooth actually show a more correct speedo reading, or closer to actual speed in the 120-170 range?

 

yes dropping a tooth on the front or adding a couple teeth on the back will make the speedo more accurate is it is running optimistic from factory..

 

Let me see, if you say that the speedo reads fast from the factory and dropping teeth in the front or gaining teeth in the rear we increase the ratio which of course causes the speedo to read fast. How will this cause the speedo to be more accurate?

 

hey fault thanks for pointing out my mistake

more teeth on the front sprocket will make the speedo more accurate if it runs optimistic from factory..

 

I tested mine with a gps

It is definitely off...

and by a lot - the percentage gets larger as speed increases.

Ie; 40mph indicates is ~35 actual. 55 indicated is 48 actual. 92 indicated is 80mph even.

I tested it with my GPS just the other day. Sucks how much bike speedos are inaccurate - same with my Suzuki.

 

FAULT

FAULT ,Thanks for the EXCEL file

 

J1603's bike shows to be 12-13% off.

My Y2K, one down in front, was off 11.5% at 60 mph. I set the yellow box accordingly and now it is right on at 60 mph.

My friend's 2001 is set up the same way as mine, however it's just a little more accurate than mine was. He decided not to use a yellow box.

So what does all this mean? Damned if I know.:beer

 

I tested a 2000 GSXR 750 and a 2000 R1 with GPS. On the average both of those bikes were about 7% high. Keep in mind these bikes are tested for top end on flat surfaces and on one day only. I have learned form doing many top end runs on many bikes that the final number can be off as much as 10 mph (indicated) from day to day, on the same road, depending on humidity and temperature. The 750 was affected greatly by these factors. What is the yellow box you guys are talking about, I have never heard of it? Is it an aftermarket speedo adjuster?

 

I tested a 2000 GSXR 750 and a 2000 R1 with GPS. On the average both of those bikes were about 7% high. Keep in mind these bikes are tested for top end on flat surfaces and on one day only. I have learned form doing many top end runs on many bikes that the final number can be off as much as 10 mph (indicated) from day to day, on the same road, depending on humidity and temperature. The 750 was affected greatly by these factors. What is the yellow box you guys are talking about, I have never heard of it? Is it an aftermarket speedo adjuster?

http://www.blackrobotics.com/desc.htm


this should help...

 

Thanks for the link!

 

I've got a couple of yellow boes for sale at 90 shipped to you vs 100 from black robotics. I bought a few to get a better price from black robotics. Exact same thing just a little cheaper. I am making no money on these. Just wanted a better deal for myself is all.

Please email me with any questions.

 

damn JL7........where are you hiding?

 

another question

If you just go up one or down one tooth on the rear sprocket will it change the speedo?

 

Yes, by a few mph. There is a formula for it that I do not have.